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Genetic counseling: Abnormal Triple Screen and Family History of PKD
Abnormal Triple Screen and Family History of PKD Introduction *What have you been told about why you are here today? *We want to discus the triple screen results and what they really mean *We want to get a family history to assess for any other risks related to pregnancy *We want to talk about the different testing options available to you. Family history update (at beginning depending on level of anxiety) *Who in the family has been diagnosed with PKD? *What age were they diagnosed? *Do any of your family members have high blood pressure? *Do any other people in your family have kidney problems? Medical History (related to PKD) *Do you see a doctor regularly? *Are you currently on any medication? *Have you had a renal ultrasound or CT scan? *Have you experienced any urinary tract infections? *Have you had high blood pressure? *Have you experienced any pain in your stomach or back? Pregnancy History *Verify dates *Any exposures? *Any cig/alcohol/drug use? *Any increase in blood pressure? *Any ultrasounds so far? When is the next one scheduled? Triple screen info. *The test itself **Best results at 16-18 weeks gestation (can be done from 15-22 weeks) **Tests mother's blood **NOT diagnostic...simply an indication for additional testing **Uses three markers to determine indicators for certain fetal problems *The three markers **produced by the fetus and the placenta **Alpha feto protein(AFP) **Human chorionic gonadotrophin (HcG) ***Most sensitive risk factor for DS ***Greater than 2.5 MOM indicated risk for DS **Estriol ***Median of 0.5 MOM in Trisomy 18 Interpreting Results *Certain combinations of levels give us an indication for possible chromosomal abnormalities *Standard results AFP =1.0, hCG =1.0, uE3 =1.0 *High AFP >2.0 or 2.5 MoM indicates ONTD ( see above) *High hCG >2.5 MoM indicates Down Syndrome(see above) *Low uE3 >0.8 MoM indicates Trisomy 18(see above) *Low AFP, high hCG, low uE3 indicates Down Syndrome *Low AFP(>0.75 MoM), low hCG(<0.55 MoM), low uE3(<0.60 MoM) indicates Trisomy 18 Patient's results *AFP = , HcG= , UE3= *Increased risk for Down syndrome Explain chromosomes and what Down syndrome is *Trisomy 21 (usually - every cell of body) *Characteristics **mental retardation (mild to moderate) **heart difficulties **ear infections **Do everything a regular kid can…ride a bike, walk, talk **Slower to reach milestones **Facial features *There is no cure Calculating risk for Down Syndrome (explain how they determine num.) *Look at maternal age + AFP MoM + hCG MoM + uE3 MoM = Down Syndrome Risk *Risk ³ 1/270 is considered screen positive **This is equal to the midtrimester DSR for 35 year-old women **AMA woman's risk may be made less by the triple screen results, but it is still considered a test positive because of her age. Recommendations for abnormal tests *Ultrasound for examination of physical abnormalities **Down Syndrome ***Nuchal fold (2nd trimester) ****detects 34% ***Nuchal translucency (1st trimester) ****detects 77% ***Short femur/humerus (detects 80-90% when combined with one of the following two) ***Echogenic bowel ***Short ear *Amniocentesis **Explain procedure **1/200 risk for complications **Can't detect all problems with the baby BUT will determine chromosome status **Fetal karyotype ***Down Syndrome ***Triploidy ***Trisomies 13, 18 ***Other chromosomal abnormalities The Basics of PKD *Definition **Multiple cysts in the kidney leading to kidney dysfunction *Prevalance = 1/400 - 1/1000 *Characteristics **90% penetrant **initial signs = high blood pressure, blood in urine (50%), pain in side, back or abdomen, UTI, kidney stones (20-30%) **Final stage = renal failure (60%) after age 40 **Mitral valve prolaspse (26% compared to gen pop 2-3%) **aneurysms (5-10%) - occurs in familial clusters **liver cysts are possible *Diagnosis/medical management **renal ultrasounds ***only after age 30 is a negative ultrasound = 5% risk of disease **computed tomography (CT) - to detect aneurysm **MRI *Prevention **Diet control = avoid red meat, eat low protein diet, less salt, fresh fruits and veggies, drink lots of water, avoid caffeine *Treatment **For pain ***acetaminophren may help ***laparoscopic surgery to "unroof" cysts **For renal failure ***dialysis ***renal transplant (75-80% of kidneys work for 5 years) *Inheritance (dominant more commonly - recessive is RARE) **Description of autosomal dominant and why this is the type **Chance of recurrence if the mother has it = 50% chance **Chance of recurrence if the mother doesn't have it same as population risk= <1%???? approximately 10% of the PKD patient community became infected through spontaneous mutation, and not through inheritance. *Genetics **Two genes identified (a third suspected) **PKD1 - 16p (90% of PKD) DX is earlier, progresses more rapidly, more likely to be hypertensive **PKD2 - chromosome 4 **Testing is done through linkage Her options *A amniocentesis for chromosome risk *A renal ultrasound for herself (PKD surveillance) **If it is negative and she is 30+, chance of having PKD is <5% *Testing by linkage analysis for herself and family **Costs approx. $2200 per family **>95% accurate in families *Prenatal determination (preferably after linkage has been established) **CVS testing for linkage studies (9-15 weeks) **Amniocentesis for linkage studies (15+ weeks) Psychosocial issues *How her brothers illness has affected her *Scared about the possibility of having PKD? *Worried about PKD for baby? *Would a diagnosis of PKD influence a pregnancy decision? *How would having a child with DS feel? *Support and resources at home? *Would the dx of DS influence pregnancy planning? Resources for patient *kidney disease access center http://www.nhpress.com/pkd/ *http://www.adam.com Notes The information in this outline has not been updated since 2003. Material obtained under GFDL Licence from http://en.wikibooks.org/wiki/Handbook_of_Genetic_Counseling